Floresorchestia amphawaensis, Suklom & Keetapithchayakul & Abdul Rahim & Wongkamhaeng, 2022

Suklom, Anotai, Keetapithchayakul, Tosaphol Saetung, Abdul Rahim, Azman & Wongkamhaeng, Koraon, 2022, Two new species of the genus Floresorchestia (Crustacea, Amphipoda, Talitridae) from Amphawa Estuary, Samut Songkhram Province, Thailand, Zoosystematics and Evolution 98 (2), pp. 285-303 : 285

publication ID	https://dx.doi.org/10.3897/zse.98.83749
publication LSID	lsid:zoobank.org:pub:5B12CCFC-3474-4FBE-8D4D-CDB971D36085
persistent identifier	https://treatment.plazi.org/id/37893B87-E408-4CDE-A8FA-B1CA22047C1F
taxon LSID	lsid:zoobank.org:act:37893B87-E408-4CDE-A8FA-B1CA22047C1F
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Floresorchestia amphawaensis
status	sp. nov.

Treatment

Floresorchestia amphawaensis sp. nov.

Type material.

Holotype. ♂, 7.8 mm, THNHM-lv-18763, THAILAND, Amphawa District, Samut Songkhram, Thailand (13°26'27.8"N, 99°57'41.3"E), 21 February 2021, Piyangkun Lueangjaroenkit; THNHM-lv-18764. Allotypes, ♀ collected with holotype; THNHM-lv-18764; Paratypes 5 ♂ and 10 ♀ collected with holotype; THNHM-lv-18765.

Type locality.

man-made ditch in coconut plantation, Amphawa District, Samut Songkhram, Thailand (13°26'27.8"N, 99°57'41.3"E).

Habitat.

Riparian-hoppers living near agricultural and urban areas in Amphawa District.

Etymology.

Named for the District of Samut Songkhram, Thailand where the species occurs.

Ecological type.

Riparian-hoppers (edges of lakes under stones or in very wet vegetation, near (or in) streams, rivers, creeks, cascades and waterfalls).

Description.

Based on holotype, male, 7.8 mm, THNHM-lv-18763.

Head (Fig. 3FA View Figure 3 ) Eye large (greater than 1/2 the length of the head). Antenna 1 (Fig. 4A1 View Figure 4 ) short, rarely longer than article 4 of antenna 2 peduncle. Antenna 2 (Fig. 4A2 View Figure 4 ) shorter than half body length; peduncular article slender; article 3 shortest; article 5 longer than article 4; flagellum with 13 articles, final article cone-shaped with an apical cluster of setae.

Upper lip (Fig. 5UL View Figure 5 ) broad, deep, apex rounded, without robust setae. Lower lip (Fig. 5LL View Figure 5 ) present; without inner plates. Left mandible (Fig. 5LMD View Figure 5 ) incisor 6-dentate; lacinia mobilis 4-dentate and four plumose setae in one row; molar strong with 16 striations and one plumose seta. Right mandible (Fig. 5RMD View Figure 5 ) incisor 5-dentate; lacinia mobilis with numerous cusps, group of three robust setae and cluster of fine setae; molar strong with 18 striations and one plumose seta. Maxilla 1 (Fig. 5MX1 View Figure 5 ) inner plate slender with two terminal plumose setae; outer plate with seven robust serrated setae; with small 1-articulate palp. Maxilla 2 (Fig. 5MX2 View Figure 5 ) plates narrow, inner plate slightly shorter than outer; with 14 subapical robust setae, one plumose seta and 9 facial setae; outer plate with 18 apical robust setae in two rows and five simple setae in outer corner. Maxilliped (Fig. 5MP View Figure 5 ) inner plate apical and subapical margins with plumose setae, robust setae and two large conical robust setae; outer plate with two rows subapical setae and plumose setae; palp article 2 distomedial lobe well developed with numerous setae; article 4 reduced, button-shaped.

Pereon. (Figs 4 View Figure 4 , 6 View Figure 6 ) Gnathopod 1 (Fig. 4G1 View Figure 4 ) sexually dimorphic; subchelate, coxa smaller than coxa 2, ventral margin lined with five robust setae, anterior margin straight; basis expanded posteriorly, anterior margin with four setae, posterodistal margin with two setae; posterior of merus, carpus and propodus each with lobe covered in palmate setae; carpus 1.5 × longer than propodus, anterior margin with two robust setae, posterior margin with four robust setae; propodus subtriangular with well-developed posterior lobe, anterior side with three groups of coupled robust setae, posterior margin with five robust setae, palm slightly serrated, lined with nine robust setae; dactylus cuspidactylate, shorter than palm.

Gnathopod 2 (Fig. 4G2 View Figure 4 ) sexually dimorphic; subchelate; coxa anterior margin with two setae and ventral margin with seven setae; basis anterior margin smooth, slightly expanded, posterior margin with three robust setae; ischium with rounded lobe on anterior margin; posterior of merus, carpus and propodus glabrous; carpus triangular, reduced, enclosed by merus and propodus, posterior lobe absent; propodus subovate, 1.4 × as long as wide, palm reaching about 34%, posteromedial surface of propodus with groove, anterior side naked, palm lined with 11 robust setae; dactylus longer than palm fitted with facial groove, attenuated distally.

Pereopod 3 (Fig. 6P3 View Figure 6 ) coxa longer than broad with posterior process, anterior margin with seven robust setae; basis slightly expanded, anterior margin with three robust setae, posterior margin with three robust setae; ischium shortest; merus longer than ischium, anterior and posterior margin of merus lined with clusters of robust setae; carpus and propodus slightly expanded; carpus posterior margin with cluster of robust setae; dactylus without notch on posterior margin.

Pereopod 4 (Fig. 6P4 View Figure 6 ) slightly shorter than pereopod 3; coxa longer than broad, anterior margin with five robust setae and with small posterior process; basis longest, posterior margin with three robust setae; ischium shortest, posterodistal with two robust setae; merus and carpus shorter than those of pereopod 3; merus distally expanded, longer than carpus and propodus, anterior and posterior margin with five robust setae; carpus shorter than propodus posterior margin with three clusters of robust setae; propodus slender, with three clusters of robust setae in posterior side; dactylus slender and longer than that of pereopod 3, thickened proximally with a notch along posterior margin.

Pereopod 5 (Fig. 6P5 View Figure 6 ) coxa bilobed, anterior lobe distinctly large than posterior lobe; basis anterior margin with five robust setae, posterior margin with row of tiny setae; merus and carpus distally expanded; carpus shorter than propodus; propodus slender, longer than merus and carpus.

Pereopod 6 (Fig. 6P6 View Figure 6 ) coxa bilobed, posterior lobe larger than anterior; basis expanded, anterior margin with 10 robust setae, posterior margin with row of tiny setae; ischium shortest; merus distally expanded, anterior side with four clusters of robust setae; carpus expanded less than merus, anterior margin lined with four clusters of robust setae; propodus slender, longer than merus and carpus; dactylus slender with subapical robust setae.

Pereopod 7 (Fig. 6P7 View Figure 6 ) coxa reduced; posterior margin of basis with distinct minute serration (each serrate with small seta), anterior margin with 10 robust setae; merus and carpus slightly expanded; propodus longer than each merus and carpus; dactylus slender with subapical robust setae.

Pleon. (Fig. 7 View Figure 7 ) Pleopods all well developed. Pleopod 1 (Fig. 7PL1 View Figure 7 ) peduncle without marginal setae; biramous, outer ramus subequal in length to peduncle; inner ramus with 11 articles; outer ramus with seven articles. Pleopod 2 (Fig. 7PL2 View Figure 7 ) peduncle without marginal setae; biramous, inner ramus subequal to outer ramus, shorter than peduncle; inner ramus with seven articles; outer ramus with six articles. Pleopod 3 (Fig. 7PL3 View Figure 7 ) peduncle without marginal setae; biramous, inner ramus subequal to outer ramus, shorter than peduncle; inner ramus with nine articles; outer ramus more than six articles.

Epimera (Fig. 7EP View Figure 7 ), Epimeron 1 posterodistal corner slightly protruding, without slit. Epimera 2 and 3 each with slits above ventral margin, with 21 and 10 slits, respectively. Epimeron 3 posteroventral corner and ventral margin smooth.

Uropod 1 (Fig. 7U1 View Figure 7 ) peduncle with four robust setae in one row; inner ramus subequal in length to outer ramus, inner ramus with five marginal robust setae, apical with three robust setae; outer ramus without marginal robust setae, apical with three robust setae. Uropod 2 (Fig. 7U2 View Figure 7 ) peduncle with three robust setae; inner ramus subequal in length to outer ramus; inner ramus with two marginal robust setae, apical with four robust setae; outer ramus with one marginal robust seta, apical with two robust setae. Uropod 3 (Fig. 7U3 View Figure 7 ) uniramous, peduncle with four robust setae; ramus subequal to peduncle, without marginal robust setae and three apical robust setae.

Telson (Fig. 7TL View Figure 7 ) as long as broad, weakly cleft, dorsal mid-line at least halfway, with one marginal, three apical robust setae and two plumose setae.

Female (Sexually dimorphic characters) (Fig. 8 View Figure 8 ). Type. Allotype, female, 8.9 mm, THNHM-lv-18764.

Pereon. Gnathopod 1 (Fig. 8G1 View Figure 8 ) merus lacking tumescent lobe, posterior margin with three robust setae; propodus without tumescent protuberance, anterior margin with three clusters of robust setae, posterior margin with six robust setae; palm slightly transverse, dactylus inner lateral posterior margin with four robust setae.

Gnathopod 2 (Fig. 8G2 View Figure 8 ) mitten-shaped; posterior margin of carpus and propodus each with lobe covered in palmate setae; carpus well developed, posterior lobe projecting between merus and propodus; nearly twice as long as wide; palm obtuse, lined with 10 robust setae, posterodistal corner with two robust setae; dactylus not modified distally, blunt.

Remarks.

Floresorchestia amphawaensis sp. nov. is similar to F. malayensis with which they share characteristics such as: (1) left mandible lacinia mobilis with 4-dentate; (2) gnathopod 1 carpus longer by 1.5 × than propodus; (3) gnathopod 2 dactylus posterior margin smooth; (4) gnathopod 2 propodus 1.4 × as long as wide; (5) uropod 1 peduncle with 4-6 robust setae; (6) uropod 3 ramus without marginal setae; (7) telson with four robust setae per lobe; (8) epimera 2-3 with slits. However, F. amphawaensis sp. nov. may be distinguished from F. malayensis by the following [Characters of F. malayensis in brackets]: (1) gnathopod 2 palm reaching 34% [palm reaching 30%]; (2) uropod 1 inner ramus with five marginal setae [four marginal setae]; (3) uropod 1 peduncle with four robust setae [with five robust setae]; (4) uropod 3 peduncle with four robust setae [two robust setae]; (5) telson slightly longer than broad [broader than long].